WO1994014932A1

WO1994014932A1 - Final-drive lubricating oil composition

Info

Publication number: WO1994014932A1
Application number: PCT/JP1993/001918
Authority: WO
Inventors: Noboru Tajima; Koji Takemitsu; Naoto Ohtsuka; Masaaki Shiomi
Original assignee: Tonen Corporation
Priority date: 1992-12-29
Filing date: 1993-12-28
Publication date: 1994-07-07
Also published as: JPH06200274A; CA2151928A1; AU5717194A; EP0677570A1; EP0677570A4

Abstract

A final-drive lubricating oil composition comprising a base oil and, added thereto, (A) 0.1-5 wt.% of a phosphoric ester, a phosphorous ester or an alkylamine salt of a phosphoric ester, (B) 0.1-5 wt.% of an organic acid represented by the general formula: R1-CON(CH¿3?)CH2COOH (wherein R?1¿ represents C¿1?-C18 alkyl or C2-C18 alkenyl) and (C) 3-15 wt.% of a sulfurized olefin or an alkyl sulfide, each based on the whole composition. The composition serves to further improve the transmission efficiency at the differential gear under varied conditions of input torque, input rotational speed and oil temperature as compared with the conventional compositions containing additives based on sulfur and phosphorous compounds, thus leading to fuel consumption improvement.

Description

Specification

Lubricating oil composition for final reduction gear

Technical field

The present invention provides a novel lubricating oil composition for final reduction gears, more specifically, compared to a conventional composition containing an SP additive, under various conditions such as input torque, input rotation speed, and oil temperature. The present invention relates to a lubricating oil composition for a final reduction gear used in automobiles such as a front engine and a rear wheel drive system, which further improves the transmission efficiency of a differential gear in a vehicle.

Conventional technology

The final reduction gear (final drive) of a car has (1) a function to further reduce the power decelerated by the transmission and change the force and direction to a right angle, and (2) the vehicle power << It has a differential function that ensures smooth operation even if a rotational differential force occurs between the left and right drive wheels.The former function is the reduction gear, and the latter is the differential gear. It is. The reduction gear is composed of a reduction gear and a reduction gear, and a high void gear is generally used as the reduction gear.

On the other hand, a differential device consists of two or four differential small gears built into a differential gear box and two differential large gears corresponding to them. The differential pinion is connected to the differential gear box by a shaft so that it can revolve around the shaft and revolve with the gear box, so that the vehicle turns and the differential rotation of the inner and outer wheels is reduced. , The difference in rotation can be absorbed mechanically.

Since the high void gear of the gear transmission mechanism used in such a final reduction gear of an automobile is exposed to severe conditions such as high-speed rotation and high load, a gear oil having excellent anti-seizure and anti-wear properties is required. For this reason, sulfur-based extreme pressure agents such as olefin sulfide and alkyl sulfide are generally used to improve anti-seizure properties, and alkyl esters of phosphates, phosphites, and phosphates are used to improve anti-wear properties. What added a phosphorus extreme pressure agent, such as a salt, to base oil is used.

However, with such conventional SP additives, gear oils with extreme pressure agents and anti-wear properties, the transmission efficiency of the differential gear is limited by the input torque, input speed, oil It is about 90-95% due to fluctuations in conditions such as temperature. This is not entirely satisfactory. Therefore, it is desired to develop a lubricating oil composition for final reduction gears that further improves the transmission efficiency of the differential gear under various conditions such as input torque, input rotation speed, and oil temperature, and improves fuel efficiency. I was Disclosure of the invention

Under such circumstances, the present invention provides a differential gear transmission under various conditions such as input torque, input rotation speed, oil temperature, and the like, in comparison with a conventional compound containing an SP additive. The purpose of the present invention is to provide a lubricating oil composition for a final reduction gear used in an automobile such as a front engine and a rear wheel drive system, which has further improved efficiency and improved fuel efficiency. . '

The present inventors have conducted intensive studies to develop a lubricating oil composition for a final reduction gear having the above-mentioned preferable properties. As a result, a phosphorus-based extreme pressure agent, a specific organic acid, It has been found that a lubricating oil composition containing a class of a sulfur-based extreme pressure agent and a sulfur-based extreme pressure agent in a predetermined ratio can achieve the object, and based on this finding, the present invention has been completed.

That is, the present invention relates to (A) at least one phosphoric acid ester selected from a phosphoric ester, a phosphite and an alkylamine salt of a phosphoric ester based on the total weight of the composition relative to the lubricating base oil. (B) — General formula [1]

R '— CON-CH ₂ — COOH …… [1]

C H:,

(R 'in the formula is an alkyl group having 1 to 18 carbon atoms or an alkenyl group having 2 to 18 carbon atoms)

0.1 to 5% by weight of an organic acid represented by the formula, and 3 to 15% by weight of at least one sulfur-based extreme pressure agent selected from (C) olefin sulfide and alkyl sulfide. It is intended to provide a lubricating oil composition for a final reduction gear characterized by the following.

Hereinafter, the present invention will be described in detail.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic view of the apparatus used in the LFW-1 friction test.

BEST MODE FOR CARRYING OUT THE INVENTION The base oil used in the lubricating oil composition of the present invention is not particularly limited, and those conventionally used as base oils for lubricating oils, for example, mineral oils and synthetic oils are used. Mineral oils include, for example, 60 Neutral oil, 100 Neutral oil, 150 Neutral oil, 300 Neutral oil, 500 Neutral oil by solvent refining or hydrorefining. And a low pour point base oil. These may be used alone or in a combination of two or more at an appropriate ratio.

On the other hand, synthetic oils include, for example, polyolefin oligomers, diesters, polyesters, polyglycols, and the like. These base oils are usually used alone, but are mixed with the mineral oil. The mixing ratio of the synthetic oil and the mineral oil is, for example, a weight ratio of 80:20 to 20:80.

The base oil used in the composition of the present invention preferably has a viscosity at 100 ° C. in the range of 3 to 20 cSt.

In the lubricating oil composition of the present invention, as the component (A), at least one selected from phosphate esters, phosphite esters and alkylamine salts of phosphate esters is used.

One type of phosphorus-based extreme pressure agent is used.

The phosphate ester (Pa) and the phosphite ester (P i) are, for example, 〇 = P (OR ² ) (OR ³ ) (OR ^), 0 = P (OH) (OR ² ) (OR ³ ) , 0 = P (OH) ₂ (OR ² ), P (OR ² ) (OR ³ ) (OR ¹ ), P (OH)

(OR ² ) (OR ³ ), P (OH), (OR ² )

Various phosphorus compounds represented by R ² , R ³ and R ″ in the above formulas each represent a linear, branched, or cyclic alkyl or alkenyl group, aryl group, or alkyl group having 4 to 30 carbon atoms, preferably 20 or less. A reel group or an alkenylalkylene oxide group, preferably an oleylethylene oxide group, which may be the same or different.

Representative of these phosphates and phosphites are:

_{_{(C l8 H 35 O) P}} (OH) 2 0 and a mixture of _{_{_{(C l8 H 35 0) 2}}} P (OH) 0 O Reiruashi' _{_{Dohosufeto, (C, 8 H 35 0}} ) 2 P (OH) Dioleyl hydrogen phosphate and oleyl ethylene oxide acid phosphate represented by Mixtures are mentioned.

On the other hand, an alkylamine salt of a phosphate ester (Pa-A) is a reaction product of a phosphate ester and an alkylamine.

0

II

^{_{(R 5 0) m P- (}} 0H) :, it ·圆_n R ^(; - such as _m ...... represented by those in (2) can be mentioned.

In the general formula (2), R ⁵ has a carbon number of 4 or more and 30 or less, preferably 20 or less, and is a linear, branched, or cyclic alkyl or alkenyl group, an aryl group or an alkyl aryl group, R ⁶ is a linear, branched, or cyclic alkyl or alkenyl group having 4 to 30 carbon atoms, preferably 20 or less, m and n are each 1 or 2, and a plurality of R ⁵ are the same And a plurality of R ⁶ may be the same or different.

In the general formula [2], R ⁵ is, for example, a butyl, hexyl, cyclohexyl, octyl, 2-ethylhexyl, decyl, lauryl, myristyl, palmityl, stearyl, oleyl, eicosyl, phenyl, cresyl group R ⁶ includes, for example, butyl, hexyl, cyclohexyl, octyl, 2-ethylhexyl, decyl, lauryl, myristyl, panolemicyl, stearyl, oleyl, eicosyl and the like.

Wherein it is a representative example of an alkyl amine salt of a phosphoric acid ester represented by the general formula [2], Jie Soo Chi Rua Cid phosphine We Ichito - Oreiruamin salt [(i one _{_{CB Η Ι7 0) 2 Ρ (}} ΟΗ) Reaction product of 0 with (C, «H ₃₅ ) NH ₂ ], and 2-ethylhexyl phosphidophosphorylamine salt.

In the composition of the present invention, one of these phosphorus-based extreme pressure agents may be used, or two or more of them may be used in combination. The amount of the phosphorus-based extreme pressure agent is based on the total weight of the composition. It is selected in the range of 0.1 to 5% by weight, preferably 0.5 to 3% by weight. If the amount is less than 0.1% by weight, a composition having excellent friction characteristics and antiwear properties will not be obtained. If it exceeds 5% by weight, no improvement will be observed for the amount, and the composition will not dissolve in the base oil. It becomes difficult. The phosphorus-based extreme pressure agent of component (A) generally has a large anti-wear effect, and also acts as an auxiliary agent to enhance the effect of the sulfur-based extreme pressure agent. Phosphate improves the friction characteristics and antiwear properties especially at the initial stage (during running-in), and phosphites have the effect of ensuring low friction properties over a long period of time, especially after running-in. In addition, alkylamine salts of phosphoric acid esters are particularly excellent in preventing gear wear.

In the lubricating oil composition of the present invention, a component represented by the general formula (1):

R'-CON-CHa-COOH ... [1]

An organic acid of a sarcosine derivative represented by CH ₃ is used. In the general formula (1), R ¹ is an alkyl group having 1 to 18 carbon atoms or an alkenyl group having 2 to 18 carbon atoms, which may be linear, branched, or cyclic. There may be. Examples of R ¹ include methyl, ethyl, propyl, butyl, pentyl, hexyl, cyclohexyl, octyl, 2-ethylhexyl, decyl, lauryl, myristyl, panolemityl, stearyl, and oleyl groups. . Among the organic acids represented by the general formula [1], oleyl sarcosinate is particularly preferred.

In the composition of the present invention, one kind of the organic acids as the component (B) may be used, or two or more kinds thereof may be used in combination. The amount of the organic acid is based on the total weight of the composition. It is selected in the range of 0.1 to 5% by weight, preferably 0.5 to 3% by weight. If this amount is less than 0.1% by weight, the effect of improving the transmission efficiency of the differential gear under various conditions such as input torque, input speed, and oil temperature will not be sufficiently exhibited, and will exceed 5% by weight. However, no improvement in the effect is recognized for the amount, and it is difficult to dissolve in the base oil.

In the lubricating oil composition of the present invention, as the component (C), at least one sulfur-based extreme pressure agent selected from among olefin sulfide and alkyl sulfide is used. As the olefin sulfide, for example, a general formula

R ⁷ -Sx-R ⁸ …… [3]

And the like. In the general formula [3], R ⁷ is an alkenyl group having 4 to 12 carbon atoms, and R ″ is an alkyl group or alkenyl group having 4 to 12 carbon atoms. Wherein R ⁷ and R ^B may be linear, branched or cyclic, and X is an integer of 1 to 8. A typical example of such an sulfide is diisobutylene sulfide (x = l).

On the other hand, as the alkyl sulfide, for example, the general formula

R ⁹ -S _y -R ^{1 0} ... [4]

And the like. In the general formula (4), R ⁹ and R ^{l (l} are each an alkyl group having 4 to 12 carbon atoms, which may be the same or different, and may be linear or branched. Y may be an integer of 1 to 8. Representative examples of such alkyl sulfides include di-t-butyl disulfide and g-t-butyl trisulfide. In the composition of the present invention, the sulfur-based extreme pressure agent of the component (C) may be used alone or in combination of two or more. It is selected in the range of 3 to 15% by weight, preferably 5 to 10% by weight based on the total weight.The sulfur-based extreme pressure agent generally forms a sulfide film on the friction surface to improve the load bearing performance of the base oil. When the content is less than 3% by weight, these effects are obtained. Is not sufficiently exhibited and becomes unsuitable as a gear oil for automobiles. If it exceeds 15% by weight, no improvement in the effect is recognized for the amount, and it is difficult to dissolve in the base oil.

In the lubricating oil composition of the present invention, various additives conventionally used in lubricating oils such as metal detergents, ashless dispersants, viscosity index improvers, and the like, as long as the object of the present invention is not impaired, Pour point depressants, antioxidants, antioxidants, corrosion inhibitors, defoamers and the like can be added as appropriate.

Examples of the metal cleaning agent include calcium sulfonate, magnesium sulfonate, barium sulfonate, calcium phosphate, barium phosphate, and the like. These are usually used at a ratio of 0.1 to 5% by weight. . Examples of the ashless detergent / dispersant include imidic succinates, succinic amides, benzylamines, boron derivatives thereof, and esters thereof, which are usually used in a ratio of 0.5 to 7% by weight. Used in.

Examples of viscosity index improvers include polymethacrylates, polyisobutylenes, ethylene-propylene copolymers, and styrene-butadiene hydrogenated copolymers. These are usually used in a proportion of 0.5 to 35% by weight. Examples of the antioxidant include amide-based antioxidants such as alkylated diphenylamine and phenyl-1-naphthylamine, 2,6-di-t-butyl-14-methylphenol, 4,4'-methylenebis (2 , 6-di-one t one-butylphenol) phenol-based antioxidants such and the like, which, as the _c-proof锖剤used generally in a proportion of 05-2% by weight, for example, alkenyl succinic acids thereof Examples of partial esters include corrosion inhibitors such as benzotriazole and benzoimidazole, and examples of antifoaming agents include dimethylpolysiloxane and polyacrylate. These can be added as appropriate.

Example

Next, the present invention will be described in more detail with reference to Examples. The present invention is not limited to these Examples.

The friction coefficient (LFW-1) and torque transmission efficiency of the actual lubricating oil composition were determined as follows.

(1) Friction coefficient (LFW-1)

Using the tester shown in Fig. 1, under the conditions of a slip speed of 1.4 mZs, load of 113 kgi and oil temperature of 100, Falex S-10 test ring (steel) and Falex H-1 60 block LFW-1 friction test was performed using (steel). In Fig. 1, 1 is the S-10 test ring, 2 is the H-60 block, and 3 is the load applied to the strain gauge _c H-60 block. Detect with a strain gauge and calculate the coefficient of friction. The test oil is soaked up to about half of the ring

(2) Actual machine torque transmission efficiency (%)

The test was conducted under the conditions of input torque: 3 kgf · m, input speed: 1,000 rpm, oil temperature: 50 ° C, and the torque transmission efficiency (%) of the actual machine was determined.

Examples 1-4, Comparative Examples 1-6

A lubricating oil composition containing a base oil (a solvent-refined mineral oil having a viscosity of 11.0 cSt at 100 ° C) and the components and types shown in Table 1 was prepared, and the coefficient of friction (LFW-1) and The torque transmission efficiency of the actual machine was determined. Table 1 shows the results. Table 1

Ll. * Λ / at Shishi; fcA ΙτΛΐ Shishi; fo ύ 例 Example Example Example Example Comparative Example Comparative Example Comparative Example Comparative Example Comparative Example Comparative Example 1 2 3 4 1 2 3 4 5 6 Isobutylene Sulfide 7.0 8.5 7.00 6.7.0 7.7.5 7.6.0 6.7.0 7.0 7.0 I 2.5% 2.5-- ― ― 2.5 ― Phosphate

Additives

Ingredients Reil sarcosinate 1.0 0 2.5 5 1. 5 ― ― ― 11 2.5 oo (wt%) 2-ethylhexylash? G '3.0 3.0 3.0 3.0 2.5

Phosphate Lairamine Salt

Giorail phosphite 1.0 2.0 2.0 2.0 2.5 2.5

0.5-0.5-0.5-0.5-0.5-year-old phosphate

Polybutenyl (acid acid) 0.5 0.5 0.5 0.5 0.5 0.5 Coefficient of friction (LFW-1) 0.063 0.060 0.063 0.065 0.088 0.090 0.087 0.085 0.075 0.077 Evaluation

Actual machine torque 94.1 94.5 94.4 94.3 92.8 92.7 92.8 92.8 93.5 93.3 Transmission efficiency)

As can be seen from Table 1, the lubricating oil composition of the present invention has a lower coefficient of friction (L FW-1) and a higher torque transmission efficiency than actual lubricating oil compositions containing conventional SP additives. Is improving.

The invention's effect

The lubricating oil composition for a final reduction gear of the present invention is obtained by mixing a base oil with a phosphorus-based extreme pressure agent and a sulfur-based extreme pressure agent in combination with an organic acid comprising a sarcosine derivative. Compared to those containing P-based additives, the transmission efficiency of the differential gear under each condition such as input torque, input rotation speed, and oil temperature is further improved, leading to improved fuel efficiency.

Claims

The scope of the claims

1. For lubricating base oil, based on the total weight of the composition, (A) at least one phosphorous extreme pressure selected from phosphate esters, phosphite esters and alkylamine salts of phosphate esters. 0.1 to 5% by weight, (B)-General formula [1]

R'-CON-CH ₂ -COOH ... [1]

I

CHn

(R ′ in the formula is an alkyl group having 1 to 18 carbon atoms or an alkenyl group having 2 to 18 carbon atoms)

0.1 to 5% by weight of an organic acid represented by the formula, and (C) 3 to 1% by weight of at least one sulfur-based extreme pressure agent selected from olefin sulfide and alkyl sulfide. A lubricating oil composition for a final reduction gear characterized by the above-mentioned.

2. The lubricating oil composition for a final reduction gear according to claim 1, wherein the lubricating base oil has a viscosity at 100 ° C of 3 to 20 cSt.

3. Phosphate and phosphite are 0 = P (OR ² ) (OR ³ ) (0 R ⁴ ), 0 == P (OH) (OR ² ) (OR ³ ), 0 = P (OH ) ₂ (OR ² ), P (OR ² ) (OR ³ ) (OR ⁴ ), P (OH) (OR ² ) (OR ³ ) or

P (OH) ₂ (OR ² )

(In the formula, R ² , R ³ and R ⁴ each represent a linear, branched or cyclic alkyl or alkenyl group, aryl group, alkylaryl group or oleylethylene having 4 to 30 carbon atoms. Are oxide groups, which may be the same or different.)

The lubricating oil composition for a final reduction gear according to claim 1, wherein the lubricating oil composition is selected from phosphorus compounds represented by the following formula:

4. Phosphate alkylamine salt has the general formula [2]

0

I!

^{_{(R 5 0) m P -}} (OH> 3 - m - (NH "R 6 3-") 3- m ...... [2]

(Wherein, R ⁵ is a linear, branched, or cyclic alkyl group having 4 to 30 carbon atoms) Or an alkenyl group, an aryl group or an alkylaryl group, R ⁶ is a linear, branched, or cyclic alkyl group or alkenyl group having 4 to 30 carbon atoms, m and n are 1 or 2, respectively. Yes, a plurality of R ⁵ may be the same or different, and a plurality of R ⁶ may be the same or different. )

2. The lubricating oil composition for a final reduction gear according to claim 1, wherein the lubricating oil composition is represented by:

5. — In the general formula [1], R ′ is methyl, methyl, propyl, butyl, pentyl, hexyl, cyclohexyl, octyl, 2-ethylhexyl, decyl, radiryl, myristyl, palmityl, stearyl and 2. The lubricating oil composition for a final reduction gear according to claim 1, which is selected from the group consisting of an oleyl group.

6. The lubricating oil composition for a final reduction gear according to claim 1, wherein the organic acid is oleyl sarcosinate.

7. Sulfur-olefin reinforced, general formula [3]

R ⁷ -S x-R ⁸ …… [3]

(In the formula, R ⁷ is an alkenyl group having 4 to 12 carbon atoms, R '' is an alkyl group or an alkenyl group having 4 to 12 carbon atoms, and R ⁷ and R ⁸ are linear or branched. And X may be an integer of 1 to 8.

The lubricating oil composition for a final reduction gear according to claim 1, which is a compound represented by the following formula:

8. The lubricating oil composition for a final reduction gear according to claim 1, wherein the olefin sulfide is diisobutylene sulfide.

9. Alkyl sulfide has the general formula [4]

R ⁹ — S _y -R ' ⁰ …… [4]

(Wherein, R ⁹ and R ^{1 11} are each the number 4 to 1 2 alkyl group having a carbon and may be the same with or different from each other, also, a linear, branched, cyclic had the Y may be an integer of up to 8.)

10. The lubricating oil composition for a final reduction gear according to claim 1, wherein the alkyl sulfide is di-tert-butyl disulfamide or di-tert-butyl trisalfide.

11. The lubricating oil composition for a final reduction gear according to claim 1, further comprising various additives commonly used in lubricating oils.

12. The claim wherein the additive is selected from the group consisting of metal detergents, ashless dispersants, viscosity index improvers, pour point depressants, antioxidants, antioxidants, corrosion inhibitors and defoamers. A lubricating oil composition for a final reduction gear according to box 11.